National Needs for Combined Sewer Overflow Control

The national extent of the combined sewer overflow problem is investigated in terms of (1)Regional populations and acreages served; and (2) a range of potential costs for the control of overflows. Combined sewers in the United States serve approx 37 million people and 2.7 million acres (10.9 × 10⁹ m²) of urban land. Cost estimates are presented for the control of runoff from combined sewer service areas based on a single design storm and eight hypothetical control strategies. Capital costs range from $1.2 billion - $68 billion (June 1973 dollars), and vary with the amount of storage and degree of treatment provided. Annual operation and maintenance expenses for the eight options range from $46 million - $400 million. These costs are compared with similar estimates for new and upgraded municipal wastewater collection and treatment systems required under Public Law 92-500.